17α-acetoxy-21-methoxy-11β-[4-N,N-dimethylaminophenyl]-19-norpregna-4,9-diene-3,20-dione) is a selective progesterone receptor modulator, it is tested for treatment of progesterone sensitive myomata.
International patent application WO 97/41145 disclosed first time the preparation of 17α-acetoxy-21-methoxy-11β-[4-N,N-dimethylaminophenyl]-19-norpregna-4,9-diene-3,20-dione). In example 9 it is characterized as light-yellow powder with a melting point of 116° C. (purity: 98.06%, characteristic FT-IR absorption bands at: 1124, 1235, 1370, 1446, 1518, 1612, 1663, 1734, 2940 cm−1).
According to WO 01/47945 and WO 01/74840 published international patent applications, the obtained 17α-acetoxy-21-methoxy-11β-[4-N,N-dimethylaminophenyl]-19-norpregna-4,9-diene-3,20-dione) was light-yellow powder as well having a melting point of 116° C. (purity: 98.87%, 98.06%, characteristic FT-IR absorption bands at: 1124, 1235, 1370, 1446, 1518, 1612, 1662, 1734, 2940 cm−1)
Final products of the above mentioned procedures were obtained by expensive purification processes. First, the crude product was purified by chromatography then after evaporation the obtained foam was treated in ultrasonic cleaner.
International patent application WO 2009001148 discloses another preparation process wherein the final product is obtained by chromatographic purification and evaporation (impurity: 0.5%, melting point: 118° C., solid-state characteristics determined by analytical technology are shown in FIG. 1-4).
Using preparation processes known in the literature, we have found that the products could not crystallize spontaneously. The purification of the crude product is expensive, difficult and not efficient enough. As the product can not be crystallized, which is the most efficient purification procedure, therefore, more difficult and expensive cleaning processes must be applied (for example chromatographic purification). The amorphous product has small grain size so the filtration thereof is quite difficult. On the one part, the unsuitable chemical stability of the amorphous form makes the drying and the storage of the product uneasy, and on the other part, the grain size and electrostatical properties of this form makes the blending, packing, sampling etc. difficult.
It must be emphasized that the pharmaceutical utility of a compound depends on the purity of the final product. To develop a reproducible large-scale preparation it is very important to obtain a product which can be filtered and dried easily. From this point of view it is also important for the product to remain stable for a long time without using any special storage conditions.
From a pharmaceutical point of view, the use of the amorphous product obtained by the above-mentioned procedures is not economical and very difficult. Thus, it is necessary to develop a process to obtain a pure crystalline product, because on the one hand, it ensures suitable pharmaceutical properties, and on the other hand, reduces the cost of the purification process significantly.
Hungarian patent application P090171 disclosed the preparation of crystalline Form A of CDB-4124. The final product was obtained by chromatographic purification of amorphous CDB-4124 followed by a crystallization process. The melting point of the product is 166-168° C. The solid-sate characteristic of anhydrate Form A was determined by IR, Raman, X-ray powder diffraction, 13C solid-state NMR measurements.
The crystalline form is unambiguously more advantageous than the amorphous form, due to its better chemical and physical stability.
In view of the pharmaceutical value of a compound, it is of prime importance to obtain it with excellent purity. It is also important to be able to synthetize it by means of a process that can readily be converted to industrial scale, especially in a form that allows rapid filtration and drying. From the above technological and product quality point of view, certain polymorphs, via a specific synthetic route, provide unique opportunity to fulfill these requirements. Therefore, there is a pharmaceutical need to find proper polymorphs and crystallization process that advantageously provides a compound in excellent purity with rapid filtration and drying properties in an industrial scale. Long-lasting, good stability without using special storage conditions is an important requirement as well.
As it is known, the less stable polymorphic form of a compound can transform into a more stable form thereof. Therefore, there is a need to find the most stable polymorphic form to avoid the polymorphic transformation, because transformation of the active ingredient may change the dissolution profile and the bioavailability of the pharmaceutical composition. Several examples are known when marketed drugs had to be withdrawn temporarily due to polymorphic transformation of the active ingredient. In order to launch them again, more development was needed and it had a considerable cost.
It has now been discovered that a more stable crystalline form of 17α-acetoxy-21-methoxy-11β-[4-N,N-dimethylaminophenyl]-19-norpregna-4,9-diene-3,20-dione) can be prepared.